This external site is not part of GS so isn't using the same code for showing the menu. You can use the same theme parts (html + css), but with different (php?) code tags, but this is depended on how theming works on that external site.

(2015-03-11, 04:22:15)shawn_a Wrote: There is no easy way as of 3.3.x to include gs as a library to do this kind of stuff.
your best best is to make a component that saves the menu as a static html file you can include.

I did that, saving menu li part to menu.txt file. No nonsense forum is html files so i had to include the menu.txt with jquery load.